Significant Dust-Obscured Star Formation in Luminous Lyman-break Galaxies at $z$$\sim$$7$$-$$8$

Sander Schouws; Mauro Stefanon; Rychard J. Bouwens; Renske Smit; Jacqueline A. Hodge; Ivo Labbé; Hiddo S. Algera; Leindert Boogaard; Stefano Carniani; Yoshi Fudamoto; Benne W. Holwerda; Garth D. Illingworth; Roberto Maiolino; Michael V. Maseda; Pascal A. Oesch; Paul P. van der Werf

doi:10.3847/1538-4357/ac4605

paper

Significant Dust-Obscured Star Formation in Luminous Lyman-break Galaxies at $z$ $\sim$ $7$ $-$ $8$

arXiv:2105.12133 · doi:10.3847/1538-4357/ac4605

Abstract

We make use of ALMA continuum observations of $15$ luminous Lyman-break galaxies at $z$ $\sim$ $7$ $-$ $8$ to probe their dust-obscured star-formation. These observations are sensitive enough to probe to obscured SFRs of $20$ $M_{⊙}$ $/$ $y r$ ( $3 σ$ ). Six of the targeted galaxies show significant ( $\geq$ $3$ $σ$ ) dust continuum detections, more than doubling the number of known dust-detected galaxies at $z$ $>$ $6.5$ . Their IR luminosities range from $2.7$ $\times$ $1 0^{11}$ $L_{⊙}$ to $1.1$ $\times$ $1 0^{12}$ $L_{⊙}$ , equivalent to obscured SFRs of $20$ to $105$ $M_{⊙}$ $/$ $y r$ . We use our results to quantify the correlation of the infrared excess IRX on the UV-continuum slope $β_{U V}$ and stellar mass. Our results are most consistent with an SMC attenuation curve for intrinsic $U V$ -slopes $β_{U V, in t r}$ of $- 2.63$ and most consistent with an attenuation curve in-between SMC and Calzetti for $β_{U V, in t r}$ slopes of $- 2.23$ , assuming a dust temperature $T_{d}$ of $50$ K. Our fiducial IRX-stellar mass results at $z$ $\sim$ $7$ $-$ $8$ are consistent with marginal evolution from $z$ $\sim$ $0$ . We then show how both results depend on $T_{d}$ . For our six dust-detected sources, we estimate their dust masses and find that they are consistent with dust production from SNe if the dust destruction is low ( $<$ $90$ %). Finally we determine the contribution of dust-obscured star formation to the star formation rate density for $U V$ luminous ( $<$ $-$ $21.5$ mag: $≳$ $1.7$ $L_{U V}^{*}$ ) $z$ $\sim$ $7$ $-$ $8$ galaxies, finding that the total SFR density at $z$ $\sim$ $7$ and $z$ $\sim$ $8$ from bright galaxies is $0.1 8_{- 0.10}^{+ 0.08}$ dex and $0.2 0_{- 0.09}^{+ 0.05}$ dex higher, respectively, i.e. $\sim$ $\frac{1}{3}$ of the star formation in $≳$ $1.7$ $L_{U V}^{*}$ galaxies at $z$ $\sim$ $7$ $-$ $8$ is obscured by dust.

21 pages, 12 figures, 2 tables. Submitted to ApJ

Significant Dust-Obscured Star Formation in Luminous Lyman-break Galaxies at $z$ $\sim$ $7$ $-$ $8$

Abstract

References in corpus (50)

Cited by in corpus (38)

Significant Dust-Obscured Star Formation in Luminous Lyman-break Galaxies at z∼7−8

Abstract

References in corpus (50)

Cited by in corpus (38)

Significant Dust-Obscured Star Formation in Luminous Lyman-break Galaxies at $z$ $\sim$ $7$ $-$ $8$